Pulmonary large-cell neuroendocrine carcinoma (LCNEC) is a rare lung malignancy characterized by an aggressive clinical course and an unfavorable prognosis. Next-generation sequencing (NGS) has reveal Show more
Pulmonary large-cell neuroendocrine carcinoma (LCNEC) is a rare lung malignancy characterized by an aggressive clinical course and an unfavorable prognosis. Next-generation sequencing (NGS) has revealed that LCNECs exhibit molecular features resembling either small-cell lung carcinoma (SCLC-like LCNEC) or non-small cell lung carcinoma (NSCLC-like LCNEC). This study aimed to characterize the incidence of actionable gene variants in a retrospective cohort of LCNEC patients using a targeted NGS approach. Microscopic diagnosis was established according to the 2021 World Health Organization (WHO) classification using a standard immunohistochemical (IHC) panel. In total, 216 LCNEC tumor samples were analyzed for molecular variants in 17 genes using the RNA-based Archer FusionPlex Lung NGS assay (Integrated DNA Technologies, USA) and the MiSeq platform (Illumina, USA)-an algorithm utilized for routine NSCLC diagnosis. Overall, 46 variants were identified in 46/216 (21.3%) tumor samples, with 28/216 (13%) LCNECs harboring at least one actionable molecular variant potentially targetable by registered or investigational agents. Show less
As the classification of kinase-driven spindle cell tumors continues to evolve, we describe the first series of pediatric mesenchymal tumors harboring FGFR1 gene fusions that share histologic overlap Show more
As the classification of kinase-driven spindle cell tumors continues to evolve, we describe the first series of pediatric mesenchymal tumors harboring FGFR1 gene fusions that share histologic overlap with infantile fibrosarcoma and "NTRK-rearranged" spindle cell neoplasms. Herein, we present three cases of FGFR1-rearranged pediatric mesenchymal tumors, including one case with FGFR1::PARD6B gene fusion and two cases with FGFR1::EBF2 gene fusion. The tumors involved infants ranging from 3 to 9 months in age with a male-to-female ratio of 2:1. All tumors involved the deep soft tissue of the gluteal, pelvic, or perirectal region. Histologically, the tumors comprised a cellular spindle cell neoplasm with primitive stellate cells, focal myxoid stroma, focal epithelioid features, no necrosis, and occasional mitotic figures (2-6 per 10 high-power field). By immunohistochemistry, the neoplastic cells focally expressed CD34 but lacked expression of S100 protein, SMA, desmin, myogenin, MyoD1, pan-TRK, and ALK. These three cases, including a case with long-term clinical follow-up, demonstrate that FGFR1 fusions occur in a subset of newly described pediatric kinase-driven mesenchymal tumors with locally aggressive behavior. Importantly, knowledge of these genetic alterations in this spectrum of pediatric tumors is key for diagnostic and targeted therapeutic purposes. Show less